1. Field of the Invention
This invention relates to electrophotographic reproducing apparatus in which sources adapted to emit flashes of high intensity light are used for effecting an instantaneous exposure, and more particularly to a light-shielding, original-document holder for such apparatus.
2. Description of the Prior Art
Generally, in an electrophotographic reproducing apparatus wherein halogen lamps emitting relatively mild light are lit for a long period of time for effecting exposure of an original document, there is used a flat holder for the original document. In this case, if the original document is relatively thick, a gap exists between the document and the holder, light leaking from the gap when exposure is effected. Light rays through the gap are not ordinarily injurious to an operator's eyes because such light rays are not very intense. In an instantaneous exposure type electrophotographic reproducing apparatus, however, particularly those using xenon lamps which emit flashes of intense light, an operator's eyes are frequently momentarily incapacitated or might even be injured due to the light rays leaking through the gap between the relatively thick original document and the flat original-document holder, because such light rays are extremely intense.
Box-like covers for accommodating thick documents in electrophotographic copiers of the instantaneous exposure type utilizing high intensity xenon lamps are also known, but if the documents, e.g., books, are larger than the support plate upon which the documents are placed for exposure, the excess portion of the document will interfere with the cover, preventing proper closure and allowing the annoying or possibly injurious light leakage. One known solution has been to provide an interlock on the cover so as to prevent copying when the thickness of the document would preclude complete shielding by the cover. The interlock is frustrating to the operator and leads to attempts, sometimes successful, to circumvent the interlock and operate the machine, subjecting the operator to the hazard of light leakage which the interlock should prevent.